Hello! playing a lot of fortnite on my old asus vg248qe monitor with 10% lightboost at 120 hz/120 fps ingame limit/vsync off, I presume that I would get a bit lower delay by turning off lightboost and running 144 hz/144 fps limit ingame or unlimited fps ingame, but the motion blur without lightboost is unacceptable for me after getting so used to lightboost/strobed,

also, anyone know how good the engine framecap is in this particular case with unreal engine 4? same as PUBG I guess but I dont play pubg, wondering if I should perhaps put unlimited fps ingame and lock to 120 fps with RTSS ? just seems unlikely that would be lower inputlag than using the ingame limiter?

thanks for any help !

Last edited by alexander1986 on 17 Jan 2019, 02:42, edited 1 time in total.

In-game limiter is best for input lag. UE 4 has a very good limiter. It's not as accurate as RTSS, but that's not important when not using vsync.

The input lag difference between 120 and 144 (both without lightboost) is negligible. It's 1000/120 - 1000/144, which is 1.4ms. Lightboost off vs on, not sure. It's more substantial, but I don't know the number. Could be 3ms, could be 6ms, don't know, really :-/ I just suspect it's around 3ms, but I could be wrong.

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RealNC wrote:In-game limiter is best for input lag. UE 4 has a very good limiter. It's not as accurate as RTSS, but that's not important when not using vsync.

The input lag difference between 120 and 144 (both without lightboost) is negligible. It's 1000/120 - 1000/144, which is 1.4ms. Lightboost off vs on, not sure. It's more substantial, but I don't know the number. Could be 3ms, could be 6ms, don't know, really :-/ I just suspect it's around 3ms, but I could be wrong.

thanks for answer! however interesting things happened when I tested rtss, with ingame limiter at 120 fps and vsync off = frametime graph is never flat, always jittery and never below 9.3 ms minimum even if fps is 120 according to rtss frame graph anyway,

with rtss limiting to 120 and fps set to unlimited ingame = frametime graph is completely flat line and solid 8.3 ms / 120 fps according to frametime graph in rtss, now I was thinking this could perhaps be because im limiting and measuring with the same program, but i'll be damned if it doesn't feel a LOT better with rtss than the ingame limiter which is soo weird imo, wish I would have tried this sooner!

I also feel on a newer system it would probably not be like this since i'm quite heavily cpu bottlenecked (i5-3470 / 8gb ram / gtx 1060 6gb) and i've never even seen it mentioned or recommended to limit with rtss in this particular game (however i've seen pubg videos showing how frametime is better/smoother with rtss, and thats same engine)

but still, weird, I will be using rtss instead of ingame limiter for the time being but what fps limit should I set in rtss just 120 or other number for best result? my monitor hz is 120.004 according to testufo site, also would you recommend prerendered frames 1 or let 3dapp decide in this case? having a hard time telling if 1 is more responsive but also more stuttery , and my cpu is pretty weak so not sure

With vsync off, the higher your FPS, the better. With a 120FPS RTSS cap, you get a tear line that's quite stationary and distracting. It might be better to cap to 180FPS or 200FPS. But if you can't maintain those frame rates consistently, then the fluctuation could become annoying.

But if the tear line doesn't bother you, then you can cap to anything you like, really.

As for pre-rendered frames, I just use 1 for everything. Some people say they get a performance drop in some rare games, but in that case it's easy to test by setting it to "app controlled" and checking whether the perf drop is indeed because of MPRF 1 or not.

Twitter • Steam • GitHub • Stack OverflowThe views and opinions expressed in my posts are my own and do not necessarily reflect the official policy or position of Blur Busters.

RTSS Scanline Sync was invented because it's perfect for LightBoost, so maybe use RTSS Scanline Sync to steer that tearline off screen.

RealNC, the reason I suggested RTSS Scanline Sync is precisely because strobing looks best with VSYNC ON, and we need ways to have an ultralow-latency VSYNC mode for games that manage to run high+consistent framerates.

Thanks to both of you for the answers! thought i'd quote both of you with some final followup questions and comments,

RealNC wrote:With vsync off, the higher your FPS, the better. With a 120FPS RTSS cap, you get a tear line that's quite stationary and distracting. It might be better to cap to 180FPS or 200FPS. But if you can't maintain those frame rates consistently, then the fluctuation could become annoying.

But if the tear line doesn't bother you, then you can cap to anything you like, really.

As for pre-rendered frames, I just use 1 for everything. Some people say they get a performance drop in some rare games, but in that case it's easy to test by setting it to "app controlled" and checking whether the perf drop is indeed because of MPRF 1 or not.

120 fps limit is the only one that I can maintain a good % of the time in this game with my bottlenecking cpu, if I turn on unlimited fps for example it will feel very very bad in terms of mouse input and the heavy load on the cpu tanks the performance and responsiveness, even if the fps is higher on average than limited 120 fps, 120 is also the highest lightboost hz for my monitor, I suppose if I had a stronger system I could try a 240 fps limit or 144-180 hz lightboost with the right monitor, also, when I set MPRF to 1 instead of default with rtss limiting, It feels slightly more stuttery both in mouse input and picture smoothness, even if it possibly feels a bit faster/snappier, maybe cause of my weak cpu not having "time" to prepare frames if its set to 1? thats my noob guess atleast

But anyway, im also still curious as to why rtss shows a completely stable frametime when I use it to limit to 120 fps instead of using the ingame limiter, with rtss limiting to 120 + vsync off = smooth frametime graph, 8.3 ms, even feels a lot better/snappier mouse/ more "direct" or "raw" input feeling than using ingame limiter 120 fps + vsync off ? also again using ingame limiter gives a very jittery frametime graph instead of the flat line when using rtss, could it just be because im limiting and measuring with the same program? (rtss) or something else here? for sure it feels better atleast with rtss which is very weird, atleast to me,

final question if I would like to try scanline sync in this particular case with fortnite (1920x1080@120hz lightboost@120 fps limit with rtss) would it be the same input latency as with vsync off/regular fps limit in rtss at 120? any quick tips on how to set up the s-sync? basically I keep vsync turned off in game+nvidia driver, and set game to unlimited fps and then enable s-sync in rtss and experiment with the tearline value? (should I try with 1 or other value for this resolution if you know?)

Thanks a lot in advance!

Chief Blur Buster wrote:Actually,

RTSS Scanline Sync was invented because it's perfect for LightBoost, so maybe use RTSS Scanline Sync to steer that tearline off screen.

RealNC, the reason I suggested RTSS Scanline Sync is precisely because strobing looks best with VSYNC ON, and we need ways to have an ultralow-latency VSYNC mode for games that manage to run high+consistent framerates.

Thanks a lot chief! maybe you have a clue about why rtss makes the frametime graph rock solid and mouse feels better when limiting with rtss to 120 fps vsync off in this game, instead of ingame limiter and vsync off and no rtss involved? also I will test scanline sync in this case soon when I get the time, but maybe you also could give your suggestion on what to set in rtss regarding scanline sync value in my case with my resolution/hz and this game? 1920x1080@120hz lightboost+vsync off like it already is I guess, and then what would you recommend I enter as scanline sync value in this case? if I could get it to look and feel as smooth as it already does just by limiting to 120 with rtss framelimiter, but without the (very minor or maybe im very tolerant to tearing) tearline I get at the moment from rtss it would be perfect, as long as the input lag is the same, or lower ofcourse

I can confidently say that now after some experimenting and some help from a friend who shared his PUBG RTSS profile where he set up scanline sync for his 1920x1080 monitor, (same game engine so thought I'd try) I can now pan the camera as fast as I want with no tearing at all, and the input lag is exactly the same as when I was just limiting the fps with riva instead of using scanline sync, only it feels even better and easier to aim without the tearing !!! even with max prerendered frames 1 its rock solid and smooth, way better than max prerendered: let 3dapp decide and no scanline sync before !!!!

( I was never bothered by the tearing before since im all about low input lag but seeing the difference now will make it impossible to go back to no scanline sync !)

frametime in the riva OSD is a completely flat line at 8.3 ms 120 fps, and my fortnite has never looked, or felt better, pulled of some kills and flickshots I never was able to do before to be honest earlier tonight lol

for anyone interested here is what I changed in the fortnite game profile in riva tuner folder:

these values might not even be optimal for the game or my setup, but all I can say is its like vsync on but no lag at ALL, if I wave the mouse like a madman then I can almost make out a slight tearline at the top of the screen, but those mouse movements are never used ingame atleast the way I play and have a pretty low sens aswell, and the focus is always in the central portions of the monitor anyway, doing the same thing without scanline sync immediately brings stuttering and tearlines even if subtle when slow mouse movement, less subtle when fast or flicking,

I've been comparing 4 different combinations quite a few times now ingame doing the same actions in the same places on the map and so on, scanline sync disabled + max prerender 1 or max prerender 3dapp decide vs scanline sync enabled + max prerender 1 or max prerender 3dapp decide, and its hilarious how much better it looks and feels with scanline sync + max prerender 1 compared to any other setting, its AMAZING!

gpu load on my gtx 1060 6gb is around 50% all the time and even with my bottlenecking old shitty i5-3470 cpu and 8gb ddr3ram its rock solid, played this game for a year and was handicapped until now lol, so thats all from me for the moment, just want to say thanks for this forum ! you guys are the best, ill maybe make a new thread just to let people know about this so they can try the same settings if they play pubg/fortnite and want to try scanline sync but are unsure what to put in the profile, maybe this can be a good start atleast for someone for me it is perfect ! really feels like old quake times with hundreds of fps on my old 150 hz CRT @ 640x480 but way better looking lol!